afa9e29272
link: https://cwiki.apache.org/confluence/display/NUTTX/Effects+of+Disabling+Interrupts+or+Pre-Emption+on+Response+Latency
42 lines
1.0 KiB
ReStructuredText
42 lines
1.0 KiB
ReStructuredText
==================================================================
|
|
Effects of Disabling Interrupts or Pre-Emption on Response Latency
|
|
==================================================================
|
|
|
|
Rate Monotonic Scheduling
|
|
=========================
|
|
|
|
**Assumption**
|
|
|
|
No resource sharing (processes do not share resources, e.g. a hardware
|
|
resource, a queue, or any kind of semaphore blocking or non-blocking
|
|
(busy-waits)).
|
|
|
|
Wikipedia “Rate Monotonic Scheduling”
|
|
|
|
**Real world**
|
|
|
|
We must protect shared resources with locks of some kind. The most aggressive:
|
|
|
|
#. Disabling interrupts, and
|
|
#. Disabling pre-emption.
|
|
|
|
What are the effects of real-time performance when this assumptions is violated?
|
|
|
|
Normal Interrupt Processing
|
|
---------------------------
|
|
|
|
.. figure:: normal_interrupt.png
|
|
:align: center
|
|
|
|
Effect of Disabling Interrupts
|
|
------------------------------
|
|
|
|
.. figure:: disabling_interrupts.png
|
|
:align: center
|
|
|
|
Effect of Disabling Pre-emption
|
|
-------------------------------
|
|
|
|
.. figure:: disabling_preemption.png
|
|
:align: center
|